Multi-primary color projection display

ABSTRACT

Embodiments of the present invention include a method, apparatus and/or system of producing a color image using four or more primary colors. The apparatus, according to some demonstrative embodiments of the invention, may include an optical arrangement to selectively split polychromatic light into at least four primary-color light beams, and to direct the at least four primary-color light beams towards at least four reflective spatial light modulators, respectively. Other embodiments are described and claimed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication No. 11/791,796, filed Aug. 7, 2008 now U.S. Pat. No.7,710,630, which is a National Phase Application of PCT InternationalApplication No. PCT/IL2005/001273, entitled “MULTI-PRIMARY COLORPROJECTION DISPLAY”, International Filing Date Nov. 29, 2005, publishedon Jun. 1, 2006 as International Publication No. WO 2006/057001, whichin turn claims priority from U. S. Provisional Patent Application No.60/631,182, filed Nov. 29, 2004, all of which are incorporated herein byreference in their entirety.

FIELD OF THE INVENTION

The invention relates generally to color display devices and methods ofdisplaying color images and, more particularly, to multi-primary colordisplays using reflective Spatial Light Modulators (SLMs).

BACKGROUND

Various types of color display technologies are known in the art. Forexample, there are CRT display systems, LCD systems, and projectiondisplay systems. In front projection displays, the projected images areviewed from a reflective viewing screen. In rear projection displays,the projected images are viewed through a transmissive viewing screen.

To produce color images, existing display devices use three primarycolors, typically, red green and blue, collectively referred to as RGB.In simultaneous projection display systems, the three primary colorcomponents of the image are modulated and displayed simultaneously usingone or more Spatial Light Modulators (SLMs).

Three primary projection displays implementing color selective retarderstack technology, e.g., as manufactured by Colorlink Incorporated, 247755th St., Boulder, Colo., 80301, USA, are described in “LCoS projectioncolor management using retarder stack technology”; Gary Sharp, MichaelRobinson, Jianmin Chen, Jonathan Birge; Elsevier Science Volume 23,2002, pp 121-128 (Reference 1), the entire disclosure of which isincorporated herein by reference.

FIG. 1 schematically illustrates an optical configuration 100 of a ROBprojection device implementing three transmissive reflective LiquidCrystal Display (LCD) panels to produce a color image, as described inReference 1.

The light from a, lamp (not shown) passes through an input polarizer 101to obtain an s-polarized white light beam. Polarizer 101 typicallyincludes a polarization conversion system followed by a clean upPolarized Beam Splitter (PBS), a sheet polarizer, or a wire-gridpolarizer, as are known in the art.

An input green/magenta filter 102 rotates the polarization, e.g., froms-polarization to p-polarization, of a green part of the spectrum of thelight received from polarizer 101. The s-polarization of other parts ofthe spectrum may be maintained.

Configuration 100 also includes a PBS 103 to transmit p-polarized light,e.g., the green light received from filter 102; and to reflect theremaining part of the light, as is known in the art. The light reflectedby PB S103 may include blue, red, and inter-primary light.

Configuration 100 also includes a single layer retarder 104. Retarder104 may have half-wave retardation in the green and zero-orientation,for correcting skew rays, as is known in the art. Retarder 104 mayenhance throughput of the green light.

Configuration 100 also includes a PBS 105, a retarder 106, and areflective LC spatial light modulator 107. PBS 105 transmits thep-polarized green light received from retarder 104 towards retarder 106.Retarder 106 may include a skew-ray correcting 0-oriented retarder withquarter-wave retardation in the green spectrum. Modulator 107 maymodulate and reflect the green light received from retarder 106, whilerotating the polarization of the reflected light, e.g., back tos-polarization. PBS 105 may reflect the s-polarized green light towardsa single layer retarder 108. Retarder 108 may have half-wave retardationin the green and zero-orientation, for correcting skew rays. Retarder108 may enhance contrast.

Configuration 100 also includes a Red-Blue ColorSelect™ filter 112 torotate the polarization, e.g., from s-polarization to p-polarization, ofa red part of the spectrum of the light reflected by PBS 103, whilemaintaining the s-polarization of the blue part of the spectrum. Filter112 may function as a zero-oriented half-wave retarder in the bluespectrum, and a π/4 oriented half-wave retarder in the red spectrum,e.g., in order to compensate for skew-ray.

Configuration 100 also includes a PBS 113, two reflective LC spatiallight modulators 114 and 115, and a Red/Blue ColorSelect™ filter 116.PBS 113 may transmit the p-polarized red light received from filter 112towards modulator 115, and reflect the s-polarized blue light towardsmodulator 114. Modulator 114 may modulate and reflect red light receivedfrom PBS 113, while rotating the polarization of the reflected light,e.g., back to s-polarization. Modulator 115 may modulate and reflectblue light received from PBS 113, while rotating the polarization of thereflected light to p-polarization. PBS 113 may reflect the s-polarizedred light towards filter 116. PBS 113 may also transmit the p-polarizedblue light towards filter 116. Filter 116 may rotate the polarization,e.g., from s-polarization to p-polarization, of the red light receivedfrom PBS 113, while maintaining the p-polarization of the blue light.

Configuration 110 also includes a combining PBS 109 to combine the red,blue, and green light beams, by transmitting the p-polarized red andblue light beams towards a filter 110; and reflecting the s-polarizedgreen light beam towards filter 110. Filter 110 includes a green/magentafilter to transmit primary blue and red p-polarized light, whilerotating the polarization of the primary green and inter-primary bandsback to p-polarization.

Configuration 100 also includes a clean-up polarizer 111 to enhancecontrast, and block inter-primary bands.

It will be appreciated by those skilled in the art, that in order toachieve desired green color coordinates, filter 102 has aparallel-polarizer blocking band that captures only a part of agreen-yellow spectrum of the white light.

SUMMARY OF SOME DEMONSTRATIVE EMBODIMENTS OF THE INVENTION

Some demonstrative embodiments of the invention include a method,apparatus and/or system of producing a color image using four or moreprimary colors.

According to some demonstrative embodiments of the invention, theapparatus may include, a first color selective rotator to selectivelyrotate the polarization of polychromatic light, and provide a firstlight beam including light of first and second spectral ranges in afirst polarization state, and light of third and fourth spectral rangesin a second polarization state, the first, second, third and fourthspectral ranges corresponding to first, second third and fourth primarycolors, respectively.

According to some demonstrative embodiments of the invention, the devicemay also include a beam splitter to split the first light beam into asecond light beam including light of the first and second spectralranges in the first polarization state, and a third light beam includinglight of the third and fourth spectral ranges in the second polarizationstate.

According to some demonstrative embodiments of the invention, the devicemay also include a second color selective rotator to selectively rotatethe polarization of the second light beam to include light of the firstspectral range in the second polarization state, and light of the secondspectral range in the first polarization state.

According to some demonstrative embodiments of the invention, the devicemay also include first and second reflective spatial light modulatorpanels including first and second arrays of pixel elements,respectively.

According to some demonstrative embodiments of the invention, the devicemay also include a first beam divider/combiner to direct the light ofthe first spectral range in the second polarization state towards thefirst reflective panel, and the light of the second spectral range inthe first polarization state towards the second reflective panel.

According to some demonstrative embodiments of the invention, the devicemay also include a third color selective rotator to selectively rotatethe polarization of the third light beam to include light of the thirdspectral range in the first polarization state, and light of the fourthspectral range in the second polarization state.

According to some demonstrative embodiments of the invention, the devicemay also include third and fourth reflective spatial light modulatorpanels including third and fourth arrays of pixel elements,respectively.

According to some demonstrative embodiments of the invention, the devicemay also include a second beam divider/combiner to direct the light ofthe third spectral range in the first polarization state towards thethird reflective panel, and the light of the fourth spectral range inthe second polarization state towards the fourth reflective panel.

According to some demonstrative embodiments of the invention, the firstreflective panel may to modulate the light of the first spectral rangein the second polarization state and reflect a first modulated lightbeam in the first polarization state carrying a first primary colorimage component of the color image; the second reflective panel may tomodulate the light of the second spectral range in the firstpolarization state and reflect a second modulated light beam in thesecond polarization state carrying a second primary color imagecomponent of the color image; the third reflective panel may modulatethe light of the third spectral range in the first polarization stateand reflect a third modulated light beam in the second polarizationstate carrying a third primary color image component of the color image;and/or the fourth reflective panel may modulate the light of the fourthspectral range in the second polarization state and reflect a fourthmodulated light beam in the first polarization state carrying a fourthprimary color image component of the color image.

According to some demonstrative embodiments of the invention, the devicemay also include a fourth color selective rotator. The first beamdivider/combiner may direct both the first and second modulated lightbeams towards the fourth rotator. The fourth rotator may selectivelyrotate the polarization of the first modulated light beam to the secondpolarization state.

According to some demonstrative embodiments of the invention, the devicemay also include a fifth color selective rotator. The second beamdivider/combiner may direct both the third and fourth modulated coloredlight beams towards the fifth rotator. The fifth rotator may selectivelyrotate the polarization of the third modulated light beam to the firstpolarization state.

According to some demonstrative embodiments of the invention, the devicemay also include a beam combiner to direct the first, second, third andfourth modulated color light beams in an output direction.

According to some demonstrative embodiments of the invention, the devicemay also include a sixth color selective rotator to rotate thepolarization of two of the first, second, third, and fourth modulatedlight beams.

According to some demonstrative embodiments of the invention, at leastone of the first and second beam divider/combiners may include apolarized beam splitter.

According to some demonstrative embodiments of the invention, each ofthe first, second, third, and fourth primary colors may include acorresponding one of green, yellow, red and blue primary colors.

According to some demonstrative embodiments of the invention, the devicemay also include comprising a projection lens to project the first,second, third and fourth modulated color light beams towards a screen.

According to some demonstrative embodiments of the invention, the devicemay also include a controller to separately activate each of the four ormore spatial light modulators to produce four or more respectivereflective patterns corresponding to four or more primary components,respectively, of a signal representing the color image.

According to some demonstrative embodiments of the invention, the devicemay also include comprising a converter to convert a three-primary colorinput signal into the signal representing the color image.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter regarded as the invention is particularly pointed outand distinctly claimed in the concluding portion of the specification.The invention, however, both as to organization and method of operation,together with objects, features and advantages thereof, may best beunderstood by reference to the following detailed description when readwith the accompanied drawings in which:

FIG. 1 is a schematic illustration of an optical configuration of aconventional RGB projection display device;

FIG. 2 is a schematic illustration of the spectral output of aconventional high-pressure mercury lamp;

FIG. 3 is a schematic illustration of an optical configuration of a fourprimary color display device in accordance with some demonstrativeembodiments of the invention;

FIG. 4 is a schematic illustration of graphs of four demonstrativeprimary color wavelength spectra, which may be implemented by thedisplay device of FIG. 3; and

FIG. 5 is a schematic illustration of a chromaticity diagramrepresenting a color gamut resulting from the primary color spectra ofFIG. 4.

It will be appreciated that for simplicity and clarity of illustration,elements shown in the drawings have not necessarily been drawnaccurately or to scale. For example, the dimensions of some of theelements may be exaggerated relative to other elements for clarity orseveral physical components included in one functional block or element.Further, where considered appropriate, reference numerals may berepeated among the drawings to indicate corresponding or analogouselements. Moreover, some of the blocks depicted in the drawings may becombined into a single function.

DETAILED DESCRIPTION OF DEMONSTRATIVE EMBODIMENTS OF THE INVENTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the invention.However, it will be understood by those of ordinary skill in the artthat the present invention may be practiced without these specificdetails. In other instances, well-known methods, procedures, componentsand circuits may not have been described in detail so as not to obscurethe present invention.

The following description of non-limiting embodiments of the inventionrelates to a projection display system using a high-pressure mercurylamp, e.g., a UHP™ 100 Watt lamp, available from Philips Lighting, adivision of Royal Philips Electronics of Eindhoven, Netherlands(“Philips UHP”), or any other suitable light source having a similarspectral range. FIG. 2 schematically illustrates the spectral output ofthe Philips UHP lamp. It will be appreciated that other types ofhigh-pressure mercury lamps may have similar spectra and/or similardesigns, and therefore the following examples may apply to many othertypes of lamps, for example, the VIP lamp available from Osram ofBerlin, Germany.

The examples herein are described in the context of high-pressuremercury type lamps because such lamps are commonly used in projectiondisplay devices. However, other types of light sources, for example,Xenon (Xe) type light sources, as are known in the art, may be used.

Embodiments of monitors and display devices with more than threeprimaries, in accordance with demonstrative embodiments of theinvention, are described in U.S. patent application Ser. No. 09/710,895,entitled “Device, System And Method For Electronic True Color Display”,filed Nov. 14, 2000, now U.S. Pat. No. 6,870,523 (Reference 1), and inInternational Application PCT/IL03/00610, filed Jul. 24, 2003, entitled“High Brightness Wide Gamut Display” and published Jan. 29, 2004 as PCTPublication WO 2004/010407 (Reference 2), the entire disclosures of allof which are incorporated herein by reference.

FIG. 3 schematically illustrates an optical configuration of a displaydevice 300 in accordance with some demonstrative embodiments of theinvention.

Although the invention is not limited in this respect, the demonstrativeconfiguration of FIG. 3 may be adapted for devices using four reflectiveSpatial Light Modulators (SLMs), e.g., reflective Liquid Crystal Display(LCD) panels, wherein each panel may produce one primary-color imagecomponent, as described below.

According to some demonstrative embodiments of the invention, device 300may include an illumination unit 301, which may include any suitablepolychromatic light source known in the art, e.g., a white light sourceas described above.

According to some demonstrative embodiments of the invention, device 300May also include an optical arrangement to selectively splitpolychromatic light of illumination unit 301 into four primary-colorlight beams, and to direct the four primary-color light beams to fourreflective SLMs, e.g., four reflective LCD panels 307, 308, 315 and 316,respectively, as described below.

It will be appreciated by those skilled in the art that that any otherarrangement may be used for producing and/or spatially modulating thefour primary-color light beams. For example, any suitable SLMconfiguration may be used instead of LCD panels 307, 308, 315 and/or316.

According to some demonstrative embodiments of the invention, device 300may also include an input polarizer 351 to receive the polychromaticlight of illumination unit 301 and to provide polychromatic light in asuitable polarization state, e.g., to produce s-polarized light orp-polarized light. Polarizer 351 may include any suitable element,system, combination and/or arrangement, e.g., including a polarizationconversion system, a clean up Polarized Beam Splitter (PBS), a sheetpolarizer, and/or a wire-grid polarizer, as are all known in the art.

According to some demonstrative embodiments of the invention, device 300may also include a first color selective rotator 302 to selectivelyrotate the polarization of the polychromatic light, and provide a firstlight beam including light of first and second spectral ranges, e.g.,corresponding to first and second primary colors, in a firstpolarization state; and light of third and fourth spectral ranges, e.g.,corresponding to third and fourth primary colors, in a secondpolarization state, as described below.

Although the invention is not limited in this respect, rotator 302 mayreceive, for example, polychromatic light, e.g., s-polarizedpolychromatic light from polarizer 351, and selectively rotate thepolarization of a part of the polychromatic light having spectral rangescorresponding to the first and second primary colors, e.g., green andyellow, to the p-polarization state. Rotator 302 may also provide one ormore other parts of the polychromatic light, for example, a part of thepolychromatic light having spectral ranges corresponding to the thirdand fourth primary colors, e.g., red and blue, in the secondpolarization state, e.g., the s-polarization state. Accordingly, thefirst light beam provided by rotator 302 may include, for example,p-polarized light of a spectral ranges corresponding to the green andyellow primary colors, and s-polarized light of a spectral rangescorresponding to the red and blue primary colors.

Color selective rotator 302 may include any suitable color selectiverotator and/or color selective filter, e.g., as are known in the art.For example, rotator 302 may include a green-yellow/red-blue filter,e.g., as is known in the art.

According to some demonstrative embodiments of the invention, device 300may also include a beam splitter 303 to split the first light beamreceived from rotator 302 into second and third light beams. The secondlight beam may include, for example, light of the first and secondspectral ranges in the first polarization state. The third light beammay include, for example, light of the third and fourth spectral rangesin the second polarization state. For example, the second light beam mayinclude p-polarized light of spectrums corresponding to the green andyellow primary colors, and the third light beam may include s-polarizedlight of spectrums corresponding to the red and blue primary colors.Beam splitter 303 may be able, for example, to transmit the second lightbeam, and to reflect the third light beam, e.g., based on thepolarization state of the second and third beams. Splitter 303 mayinclude any suitable beam splitter. For example, splitter 303 mayinclude a PBS able to reflect s-polarized light, and to transmitp-polarized light, e.g., as is known in the art.

According to some demonstrative embodiments of the invention, device 300may also include a second color selective rotator 304 to selectivelyrotate the polarization, e.g., to the s-polarization state, of a part ofthe second light beam having a spectral range corresponding to the firstprimary color. For example, rotator 304 may be able to rotate the partof the second light beam having a spectral range corresponding to thegreen primary color. Rotator 304 may also maintain, for example, thepolarization state of the part of the second light beam having aspectrum corresponding to the yellow primary color. Accordingly, lightprovided by rotator 304 may include s-primary light corresponding to thefirst primary color, e.g. green; and p-polarized light corresponding tothe second primary color, e.g., yellow.

Although the invention is not limited in this respect, rotator 304 mayalso be adapted to perform a skew-ray compensation of the second lightbeam. For example, rotator 304 may function as a zero-oriented Half WaveRetarder (HWR) with respect to light of the second primary color, e.g.,yellow, to produce, for example, a λ/2 phase shift in the lightcorresponding to the yellow primary color; and a π/4-oriented HWR withrespect to the light of the first primary color, e.g., green, toproduce, for example, a λ/2 phase shift in the light corresponding tothe green primary color.

Rotator 304 may include any suitable optical element, filter,configuration, arrangement, and/or system. For example, rotator 304 mayinclude the green-yellow ColorSelect™ rotator manufactured by ColorLink,Inc., 5335 Sterling Dr Suite B, Boulder, Colo., 80301, USA.

According to some demonstrative embodiments of the invention, device 300may also include a first beam divider/combiner 305 to split the lightfrom rotator 304, and direct the light of the first spectral range inthe second polarization state towards panel 308, and the light of thesecond spectral range in the first polarization state towards panel 307.Beam divider/combiner 305 may be able, for example, to transmit a firstpart of the light received from rotator 304 and to reflect a second partof the light received from rotator 304, e.g., based on the polarizationstate of the first and second parts of the light received from rotator304. For example, beam divider/combiner 305 may direct a green lightbeam towards panel 308, e.g., by reflecting the s-polarized lightcorresponding to the green spectrum; and a yellow light beam towardspanel 307, e.g., by transmitting the p-polarized light corresponding tothe yellow spectrum. Beam divider/combiner 305 may include any suitablebeam splitter. For example, beam divider/combiner 305 may include a PBSable to reflect s-polarized light, and to transmit p-polarized light,e.g., as is known in the art.

According to some demonstrative embodiments of the invention, device 300may also include a retarder 306 to perform a skew correction to theyellow light beam. For example, retarder 306 may include a zero-orientedretarder having quarter-wave retardation in the yellow spectrum, e.g.,as is known in the art.

According to some demonstrative embodiments of the invention, device 300may also include a third color selective rotator 313 to selectivelyrotate the polarization, e.g., to the p-polarization state, of a part ofthe third light beam having a spectral range corresponding to the thirdprimary color. For example, rotator 313 may be able to rotate the partof the third light beam having a spectral range corresponding to the redcolor. Rotator 313 may also maintain, for example, the polarizationstate of the part of the third light beam having a spectrumcorresponding to the blue primary color. Accordingly, light provided byrotator 313 may include p-polarized light corresponding to the thirdprimary color, e.g., red; and s-primary light corresponding to thefourth primary color, e.g., blue.

Although the invention is not limited in this respect, rotator 313 mayalso be adapted to perform a skew-ray compensation of the third lightbeam. For example, rotator 313 may function as a zero-oriented HWR withrespect to light of the fourth spectral range, e.g., blue, to produce,for example, a λ/2 phase shift in the light corresponding to the blueprimary color; and a π/4-oriented HWR with respect to the light of thethird spectral range, red, to produce, for example, a λ/2 phase shift inthe light corresponding to the red primary color.

Rotator 313 may include any suitable optical element, filter,configuration, arrangement, and/or system. For example, rotator 313 mayinclude the red-blue ColorSelect™ rotator manufactured by ColorLink,Inc., 5335 Sterling Dr Suite B, Boulder, Colo., 80301, USA.

According to some demonstrative embodiments of the invention, device 300may also include a second beam divider/combiner 314 to split the lightfrom rotator 313, and direct the light of the third spectral range inthe first polarization state, e.g., the p-polarization state, towardspanel 316; and the light of the fourth spectral range in the secondpolarization state, e.g., the s-polarization state, towards panel 315.Beam divider/combiner 314 may be able, for example, to transmit a firstpart of the light received from rotator 313 and to reflect a second partof the light received from rotator 313, e.g., based on the polarizationstate of the first and second parts of the light received from rotator313. For example, beam divider/combiner 314 may direct a blue light beamtowards panel 315, e.g., by reflecting s-polarized light correspondingto the blue spectrum; and a red light beam towards panel 316, e.g., bytransmitting p-polarized light corresponding to the red spectrum. Beamdivider/combiner 314 may include any suitable beam splitter. Forexample, beam divider/combiner 314 may include a PBS able to reflects-polarized light, and to transmit p-polarized light, e.g., as is knownin the art.

According to some demonstrative embodiments of the invention, one ormore of panels 307, 308, 315 and 316 may include an array of pixels, asis known in the art, which may be selectively activated to produce areflective pattern corresponding to one of a plurality of primary colorimages. In the example described herein, one or more of panels 307, 308,315 and/or 316 may be separately activated by a controller 369 toproduce a reflective pattern corresponding to one of four independentprimary color images, in accordance with an input signal 377representing a four-primary-color image. Such an input signal may begenerated using any of the methods described in Reference 1 and/orReference 2, e.g., using a converter 371 to convert athree-primary-color image signal 398 into a four-primary-color imagesignal. Each reflective pattern may modulate a corresponding primarycolor light beam to produce a corresponding primary color imagecomponent.

According to some demonstrative embodiments of the invention, one ormore pixels of reflective panels 307, 308, 315 and/or 316, whenactivated to an “on” state, may reflect polarized light, as is known inthe art. Accordingly, pixels of reflective panels 307, 308, 315 and/or316, when at an “off” state, may substantially block reflectance ofpolarized light, as is known in the art. Thus, in accordance with theseembodiments of the invention, panels 307, 308, 315 and/or 316 may becontrolled, e.g., as described above, to produce four modulated primarycolor light beams, respectively, carrying four, respective, primarycolor image components. For example, controller 369 may control panel308 to modulate the first primary color light beam, e.g., the greenlight beam, to produce a first, e.g., green, modulated light beam; panel307 to modulate the second primary color light beam, e.g., the yellowlight beam, to produce a second, e.g., yellow, modulated light beam;panel 316 to modulate-the third primary color light beam, e.g., the redlight beam, to produce a third, e.g., red, modulated light beam; and/orpanel 315 to modulate the fourth primary color light beam, e.g., theblue light beam, to produce a fourth, e.g., blue, modulated light beam.

According to some demonstrative examples of the invention, panel 307 maybe configured to rotate the polarization of the reflected second primarycolor light beam from p-polarization to s-polarization; panel 308 may beconfigured to rotate the polarization of the reflected first primarycolor light beam from s-polarization to p-polarization; panel 316 may beconfigured to rotate the polarization of the reflected third primarycolor light beam from p-polarization to s-polarization; and/or panel 315may be configured to rotate the polarization of the reflected fourthprimary color light beam from s-polarization to p-polarization. Forexample, one or more pixels of panels 308 and/or 316, when activated toan “on” state, may reflect the green and/or red light beams,respectively, while rotating the polarization of the reflected lightfrom s-polarization to p-polarization; and/or one or more pixels ofpanels 307 and/or 315, when activated to an “on” state, may reflect theyellow and/or blue light beams, respectively, while rotating thepolarization of the reflected light from p-polarization tos-polarization.

According to some demonstrative embodiments of the invention, device 300may also include a fourth color selective rotator 309. Beamdivider/combiner 305 may be able to direct both the first and secondmodulated light beams, e.g., the green and yellow modulated light beams,towards rotator 309. For example, divider/combiner 305 may reflect thes-polarized modulated yellow light beam, and transmit the p-polarizedmodulated green light beam.

According to some demonstrative embodiments of the invention, rotator309 may selectively rotate the polarization of the first modulated lightbeam, e.g., the green modulated light beam, to the second polarizationstate, e.g., the s-polarization state. Rotator 309 may include anysuitable color selective rotator or filter, e.g., a green-yellowColorSelect™ rotator manufactured by ColorLink, Inc., 5335 Sterling DrSuite B, Boulder, Colo., 80301, USA.

According to some demonstrative embodiments of the invention, device 300may also include a fifth color selective rotator 317. Beamdivider/combiner 314 may be able to direct both the third and fourthmodulated light beams, e.g., the red and blue modulated light beams,towards rotator 317. For example, divider/combiner 314 may reflect thes-polarized modulated red light beam, and transmit the p-polarizedmodulated blue light beam.

According to some demonstrative embodiments of the invention, rotator317 may selectively rotate the polarization of the third modulated lightbeam, e.g., the blue modulated light beam, to the first polarizationstate, e.g., the p-polarization state. Rotator 317 may include anysuitable color selective rotator or filter, e.g., a red-blueColorSelect™ rotator manufactured by ColorLink, Inc., 5335 Sterling DrSuite B, Boulder, Colo., 80301, USA.

According to some demonstrative embodiments of the invention, device 300may also include a beam combiner 310 to direct the first, second, thirdand/or fourth modulated light beams in an output direction, e.g.,towards a projection lens 369. For example, beam combiner may reflectthe s-polarized first and second primary color modulated light beams,e.g., the s-polarized modulated green and yellow light beams; andtransmit the p-polarized third and fourth modulated light beams, e.g.,the p-polarized modulated red and blue light beams. Beam combiner 310may include any suitable beam combiner, e.g., a PBS.

According to some demonstrative embodiments of the invention, device 300may also include a sixth color selective rotator 311 to selectivelyrotate the one or more of the modulated light beams, e.g., such that allfour modulated light beams have the same polarization. For example,rotator 311 may rotate the polarization of the red and blue light beamsfrom p-polarization to s-polarization. Alternatively, rotator 311 mayrotate the polarization of the green and yellow light beams froms-polarization to p-polarization.

Color selective rotator 31 may include any suitable color selectiverotator and/or color selective filter, e.g., as are known in the art.For example, rotator 311 may include a green-yellow/red-blue filter,e.g., as is known in the art.

According to some demonstrative embodiments of the invention, device 300may also include a clean-up polarizer 312, e.g., to enhance contrast asis known in the art.

According to some demonstrative embodiments of the invention, projectionlens 369 may include any suitable projection lens, e.g., as is known inthe art, to project the first, second, third, and/or fourth modulatedlight beams onto a screen 327.

FIG. 4 schematically illustrates graphs of four exemplary primary colorwavelength spectra, which may be implemented by the color display ofFIG. 3.

FIG. 4 shows the wavelength spectra of a set of four primary colorswhich may correspond, for example, to the first, second, third and/orfourth spectral ranges, respectively, implemented by filters 302, 304,313, 309, 317, and/or 311.

According to some demonstrative embodiments of the invention, thespecific color choices of the primary color wavelength ranges shown inFIG. 4 may result in significantly wider color gamut and/or imagebrightness, compared to prior art RGB color display devices, asdescribed below.

FIG. 5 schematically illustrates a chromaticity diagram representing theresulting color gamut of the primary color spectra of FIG. 4.

As clearly shown in FIG. 5, the color gamut produced by a theoreticalNTSC gamut display is substantially covered by the gamut of the fourprimary colors of FIG. 4. As further shown, in FIG. 5, the white pointcoordinates obtained by the sum of all primaries are x=0.313 andy=0.329. The luminance values for the colors obtained by thisconfiguration are in general equal to or higher than the luminancevalues that can be obtained for the same colors from a theoretical NTSCgamut display. Thus, in general, all the colors that can be reproducedby a theoretical NTSC gamut display are also reproducible by the primarycolor selections of FIG. 5, both in terms of color coordinates and interms of intensity.

It should be appreciated that although the primary color selections ofFIG. 4 provide desirable results in terms of image color and brightness,there may be other suitable selections of four primary colors thatprovide similar (or even better) results, in accordance with specificimplementations.

Some demonstrative embodiments of the invention may relate to methodsand/or devices of displaying a color image using four primary colors,e.g., as described above with reference to FIGS. 3-5. However, it willbe appreciated by those of ordinary skill in the art that otherembodiments of the invention may be implemented for displaying a colorimage using more than four primary colors. For example, it will beappreciate by those skilled in the art that the device of FIG. 3 may bemodified to enable displaying a color image using five or more primarycolors, e.g., by adding one or more color selective rotators and/or oneor more reflective SLM panels.

While certain features of the invention have been illustrated anddescribed herein, many modifications, substitutions, changes, andequivalents may occur to those of ordinary skill in the art. It is,therefore, to be understood that the appended claims are intended tocover all such modifications and changes as fall within the true spiritof the invention.

1. A display device of producing a color image using four or moreprimary colors, the device comprising: a first color selective rotatorto selectively rotate the polarization of polychromatic light, andprovide a first light beam including light of first and second spectralranges in a first polarization state, and light of third and fourthspectral ranges in a second polarization state, said first, second,third and fourth spectral ranges corresponding to first, second thirdand fourth primary colors, respectively; a beam splitter to split saidfirst light beam into a second light beam including light of said firstand second spectral ranges in said first polarization state, and a thirdlight beam including light of said third and fourth spectral ranges insaid second polarization state; a second color selective rotator toselectively rotate the polarization of said second light beam to includelight of said first spectral range in said second polarization state,and light of said second spectral range in said first polarizationstate; first and second reflective spatial light modulator panelsincluding first and second arrays of pixel elements, respectively; afirst beam divider/combiner to direct the light of said first spectralrange in said second polarization state towards said first reflectivepanel, and the light of said second spectral range in said firstpolarization state towards said second reflective panel; a third colorselective rotator to selectively rotate the polarization of said thirdlight beam to include light of said third spectral range in said firstpolarization state, and light of said fourth spectral range in saidsecond polarization state; third and fourth reflective spatial lightmodulator panels including third and fourth arrays of pixel elements,respectively; and a second beam divider/combiner to direct the light ofsaid third spectral range in said first polarization state towards saidthird reflective panel, and the light of said fourth spectral range insaid second polarization state towards said fourth reflective panel. 2.The device of claim 1, wherein said first reflective panel is able tomodulate the light of said first spectral range in said secondpolarization state and reflect a first modulated light beam in saidfirst polarization state carrying a first primary color image componentof said color image; said second reflective panel is able to modulatethe light of said second spectral range in said first polarization stateand reflect a second modulated light beam in said second polarizationstate carrying a second primary color image component of said colorimage; said third reflective panel is able to modulate the light of saidthird spectral range in said first polarization state and reflect athird modulated light beam in said second polarization state carrying athird primary color image component of said color image; and said fourthreflective panel is able to modulate the light of said fourth spectralrange in said second polarization state and reflect a fourth modulatedlight beam in said first polarization state carrying a fourth primarycolor image component of said color image.
 3. The device of claim 2comprising a fourth color selective rotator, wherein said first beamdivider/combiner is able to direct both said first and second modulatedlight beams towards said fourth rotator, and wherein said fourth rotatoris able to selectively rotate the polarization of said first modulatedlight beam to said second polarization state.
 4. The device of claim 3comprising a fifth color selective rotator, wherein said second beamdivider/combiner is able to direct both said third and fourth modulatedcolored light beams towards said fifth rotator, and wherein said fifthrotator is able to selectively rotate the polarization of said thirdmodulated light beam to said first polarization state.
 5. The device ofclaim 4 comprising a beam combiner to direct said first, second, thirdand fourth modulated color light beams in an output direction.
 6. Thedevice of claim 5 comprising a sixth color selective rotator to rotatethe polarization of two of said first, second, third, and fourthmodulated light beams.
 7. The device of claim 1, wherein at least one ofsaid first and second beam divider/combiners comprises a polarized beamsplitter.
 8. The device of claim 1, wherein each of said first, second,third, and fourth primary colors comprises a corresponding one of green,yellow, red and blue primary colors.
 9. The device of claim 1 comprisinga projection lens to project said first, second, third and fourthmodulated color light beams towards a screen.
 10. The device of claim 1comprising a controller to separately activate each of said four or morespatial light modulators to produce four or more respective reflectivepatterns corresponding to four or more primary components, respectively,of a signal representing said color image.
 11. The device of claim 10comprising a converter to convert a three-primary color input signalinto the signal representing said color image.
 12. A method of producinga color image using four or more primary colors comprising: selectivelyrotating the polarization of polychromatic light to provide a firstlight beam including light of first and second spectral ranges in afirst polarization state, and light of third and fourth spectral rangesin a second polarization state, said first, second, third and fourthspectral ranges corresponding to first, second third and fourth primarycolors, respectively; splitting said first light beam into a secondlight beam including the light of said first and second spectral rangesin said first polarization state, and a third light beam including thelight of said third and fourth spectral ranges in said secondpolarization state; selectively rotating the polarization of said secondlight beam to include light of said first spectral range in said secondpolarization state, and light of said second spectral range in saidfirst polarization state; directing the light of said first spectralrange in said second polarization state towards a first reflectivepanel, and the light of said second spectral range in said firstpolarization towards a second reflective panel; selectively rotating thepolarization of said third light beam to include light of said thirdspectral range in said first polarization state, and light of saidfourth spectral range in said second polarization state; and directingthe light of said third spectral range in said first polarization statetowards a third reflective panel, and the light of said fourth spectralrange in said second polarization state towards a fourth reflectivepanel.
 13. The method of claim 12 comprising: modulating the light ofsaid first spectral range in said second polarization state, andreflecting a first modulated light beam in said first polarization statecarrying a first primary color image component of said color image;modulating the light of said second spectral range in said firstpolarization state and reflecting a second modulated light beam in saidsecond polarization state carrying a second primary color imagecomponent of said color image; modulating the light of said thirdspectral range in said first polarization state and reflecting a thirdmodulated light beam in said second polarization state carrying a thirdprimary color image component of said color image; and modulating thelight of said fourth spectral range in said second polarization stateand reflecting a fourth modulated light beam in said first polarizationstate carrying a fourth primary color image component of said colorimage.
 14. The method of claim 13 comprising selectively rotating thepolarization of said first modulated light beam to said secondpolarization state.
 15. The method of claim 14 comprising selectivelyrotating the polarization of said third modulated light beam to saidfirst polarization state.
 16. The method of claim 15 comprisingdirecting said first, second, third and fourth modulated color lightbeams in an output direction.
 17. The device of claim 16 comprisingselectively rotating the polarization of two of said first, second,third, and fourth modulated light beams.
 18. The method of claim 12,wherein each of said first, second, third, and fourth primary colorscomprises a corresponding one of green, yellow, red and blue primarycolors.
 19. The method of claim 12 comprising projecting said first,second, third and fourth modulated color light beams towards a screen.